Thesis (M.Sc.)--Chulalongkorn University, 2005

Objective: To compare the results between 2-hour daytime polysomnography (PSG) and overnight PSG (as gold standard) to screen high risk snorers. Study design: Descriptive study (Diagnostic test) Setting: Snoring clinic, Phramongkutklao hospital Method and material: This study included patients with high risk of obstructive sleep apnea and were scheduled for overnight PSG at the snoring clinic, Phramongkuthklao Hospital between September 2005 and February 2006. Two-hour DPSG was conducted with midazolam induction. ONPSG was performed as the gold standard procedure within 2 months before DPSG. These patients had to have Epworth Sleepiness Scale (ESS)>= 8/24 and/or BMI more than 27.5. Patients were categorized into high risk obstructive sleep apnea syndrome (OSAS) (AHI>=20/Hr) and low risk OSAS (AHI <20/HR). Regarding snoring sound, it was divided in 3 groups: 1 = mild, 2 = moderate, 3 = severe. Results: Fifty patients, 31 Males and 17 Females were participated in this study with the mean age of 48.3+-10.6 year (range 22-65), BMI of 27.7+-3.9 (22.5-36.9) and ESS of 10.6+-2.3. By categorized the patients into high risk OSAS and low risk OSAS, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of DPSG comparing with ONPSG were 92% 91.3% 92.% and 91.3% The agreement (kappa statistics) of snoring sounds in daytime and night time was 0.72 Conclusion: This study revealed the DPSG had a high sensitivity and specificity. Therefore it should be used as a good screening test for high risk snorers and was very helpful to assess the outcomes of OSAS patients after surgical intervention.